This invention relates generally to resuscitation devices and, more particularly, to an emergency resuscitation apparatus having an external assembly for setting a volume of air expelled from an outflow port as may be appropriate based on the size or age of a patient.
An emergency resuscitator is a portable device, commonly referred to as a bag-valve-mask, that may be manually operated to repeatedly inflate the lungs of a patient who is in pulmonary arrest, i.e. is not breathing on his own or in patients in respiratory distress secondary to inadequate ventilation and are in need of ventilator assistance. The use of a portable resuscitator, whether in a hospital setting or at the scene of a medical emergency, can be the difference between life or death.
The current resuscitator as it is currently designed was invented in 1953 and was first marketed in 1956. Therefore, there has been no significant design or functional advancement in this device in 60 years.
One problem with current bag-valve-mask resuscitator devices is that they can potentially expel volumes of air significantly larger than that appropriate for the patient. For instance, the lung capacity of a full-grown man is much larger than the capacity of an infant or a child. It is common, with the current technology, for a manufacturer to produce three different sizes of resuscitators: adult, child and infant. To prevent causing injury while using a resuscitator, this requires medical personnel to either choose one of these portable resuscitators specifically designed and adapted for the approximate size of the patient, or simply “estimate” how much to squeeze the resuscitator bag. The potential for causing injury to a patient due to lung over expansion, therefore, is obvious.
The design of the current resuscitator is extremely inefficient. As an example, current resuscitator devices designed for use in the adult patient have air reservoirs containing volumes of approximately 1600-1800 ml depending on the manufacturer. However, they are designed to deliver only 500-700 ml with each squeeze or activation of the device. This allows for a residual amount of air retained in the bag of approximately 1000 ml and therefore, if used improperly, can result in significant over inflation of the patient's lungs and potentially causing alveolar damage. Similar reservoir volume vs volume delivered discrepancies exist with the child and infant versions of the device.
Another deficiency associated with the current manual resuscitator design concept is inconsistency/reproducibility of the volume of air delivered with each activation. The design (football shaped, which is ergonomically extremely poor) and the reservoir volume versus volume delivered discrepancy create an environment where it is extremely difficult, and almost impossible, for the current devices to perform up to published specifications regarding delivered volumes in a consistent and reproducible way in multiple scenarios. Several examples can be cited. First would be differences found when the same device is activated by two different operators who have different size hands and different grip strengths. A second would be seen when the same operator repeatedly activates the same device over time wherein a degree of grip fatigue and strength would have a definite impact. A third would be the fact that during a resuscitation procedure, the operator does not consciously concentrate on the activation function of the device because his/her attention is directed elsewhere. Still another fact is that volume delivered specifications vary as much as 100 to 150 ml per activation of the adult version from manufacturer to manufacturer, therefore, producing a volume delivered discrepancy from device to device.
One portable resuscitator that is the subject of U.S. Pat. No. 8,936,024 recognized a need to selectively limit a volume of air expelled from an outlet. Although presumably effective for its intended use, the '024 patent utilizes a complicated assembly that includes a myriad of index pins positioned in a void and multiple cords and cord anchors which must be set to infant, child, or adult settings. The setting of the volume controls of the '024 design are limited to these three approximate volume settings and do not provide for more incremental volume selections for appropriate use. Another significant disadvantage of the '024 design is that in the event of a malfunction of the internal structure of the volume control mechanism it would not be visible to and may not be detected by the operator, because there would be no external indication of the malfunction, making it possible to deliver an inappropriate volume of air to the patient (either too low or too high).
Therefore, it would be desirable to have an emergency resuscitator apparatus having an external control mechanism for limiting a maximum volume of air to be expelled each time a bellows is operated and that delivered volume be more accurate and reproducible than the current technology allows. Further, it would be desirable to have an emergency resuscitator apparatus that may be set to a specific volumetric level (measured in milliliters) to be expelled by the apparatus. Also, it would be desirable to have an emergency resuscitator apparatus that may be set to a multitude of volume settings as compared to only three settings available in the '024 design in order to accommodate the desirable expelled volumes of air calculated for various sizes of individuals that lie between and over those settings provided for by the '024 design. In addition, it would be desirable to have an emergency resuscitator apparatus having a volume limiting flange that prevents the opening of a top plate of a bellows beyond an amount corresponding to a selected volume of air to be expelled by the resuscitator thereby providing a safety mechanism preventing over inflation of the lungs.